There have been known synchrotron radiation and technologies to transform synchrotron radiation into polarized X-ray. The synchrotron radiation is usually known to be high luminance of white radiation in the range from 1 keV to 100 keV. The synchrotron radiation is usually linearly polarized radiation and the radiation can be transformed into horizontally polarized radiation by passing relativistic electron beam in the inside of a deflecting electromagnet or linear undulator which is attached to the synchrotron accelerator. The horizontal polarization is transformed into circular polarization or vertical polarization through a polarizer (phase shifter). For example, the horizontal-linear polarization of 45-degrees in azimuth angle is transformed into the right circular polarization by passing through a λ/4 polarizing plate, the horizontal-linear polarization of—45-degrees in azimuth angle is transformed into the left circular polarization by passing through λ/4 polarizing plate, the horizontal-linear polarization is transformed into the vertical-linear polarization by passing through a λ/2 polarizing plate. This method makes the transformation of linearly-polarized soft X-ray into other polarized soft X-ray possible, but the conversion efficiency is very low. The linearly-polarized hard X-ray is alternately transformed into right circularly polarized X-ray and left circularly polarized X-ray by oscillating periodically a transmission polarizer such as crystallite silicon or diamond. For the electrical oscillation of the transmission polarizer, for example, piezoelectric devices and galvanoscanners are used. It has been known that the maximum speed of polarization-switching being performed by the piezoelectric device and galvanoscanner is about 100 Hz (10 ms) and 2 kHz (0.5 ms), respectively. However, a switching of 2 kHz (0.5 ms) makes polarized X-ray analysis of static samples possible but makes that of biological samples impossible. The method to generate polarized X-ray using the circular accelerators such as synchrotron and cyclotron may be never used for industrial usages due to the huge apparatus of several kilometers in circumferential length.
X-ray free electron laser (SACLA) has been known as coherent X-ray. The SACLA is very big facilities, so unavailable for industrial usages.
On the other hand, the laser inverse Compton scattering X-ray generator using an optical resonator and accelerated electron beam has been known. Since the generator is able to use a compacted accelerator for the accelerated electron beam source, the generator has a great advantage over the Spring-8 and SACLA in industrial prevalence. Therefore, development of the laser inverse Compton scattering X-ray generator using an optical resonator as is capable of generation coherent X-ray is bound to provide immeasurably great effects to the industrial availability.
An optical resonator to amplify coherent laser has been presented (Patent Literature 1).
The Patent Literature 1 discloses a 4-mirror optical resonator that has a detuned concentric configuration as each middle point of the optical path lines in the same straight line (see FIG. 1 in the Patent Literature 1). However, the Patent Literature 1 nowhere describes or suggests an optical resonator to prepare polarized laser.
Regarding to the X-ray generator to generate laser inverse Compton scattering X-ray by using the optical resonator, for example, the following several patent literatures have been presented (Patent Literatures 2-4).
The Patent Literature 2 discloses the apparatus to generate short-wavelength light by collision between laser being repeatedly reflected in the inside of the optical resonator, which providing a unit of multi concave mirrors arranged with a pair of concave mirrors in series, and electron beam being introduced into the optical resonator: wherein, the laser beam is in repetition reflected and focused between the concave mirrors and the collision of the laser beam and electron beam is carried out in the focused region of the laser beam. Because this apparatus in which the mode-locked laser is merely reflected through a pair of concave mirrors is, in structure, the same as the Fox-Smith interferometer-typed optical resonator, the amplification of the laser beam produced by the apparatus is limited to at most 1,000 times in gain due to limitation of the resonator length control. Therefore, the apparatus may generate short-wavelength light for a photolithography usage as described in the literature, but cannot generate strong laser inverse Compton scattering X-ray. Also, the apparatus can generate neither polarized laser nor polarized-X-ray.
The Patent Literature 3 discloses the apparatus to generate X-ray by collision of laser and electron beam in the inside of the Fox-Smith interferometer-typed resonator having a laser oscillator between a pair of mirrors which is put in the electron beam loop-path of the circular accelerators. Because laser is provided only by the laser oscillator, the amplification of the laser supplied by the laser oscillator is limited to at most 1,000 times in gain as explained above, even if reflectance of the reflecting mirrors is much raised. Therefore, it is difficult to generate strong laser inverse Compton scattering X-ray. The apparatus can generate neither polarized laser nor polarized X-ray.
The Patent Literature 4 discloses the apparatus to generate X-ray or γ-ray by collision between laser and electron beam in the inside of the Fox-Smith interferometer-typed optical resonator providing a pair of mirrors with super reflectance that is placed in the electron beam loop-path of the circular accelerators. Also, the invention discloses the apparatus providing a set of the resonators aligning in parallel on the electron beam orbit. However, the optical resonator used in the apparatus is the conventional resonator providing a pair of concave mirrors. Even if the mirrors with 99.99984% in reflectance can be used, the amplification of laser is limited to at most 1,000 times as explained above. Therefore, the apparatus cannot generate strong laser inverse Compton scattering X-ray. The apparatus can neither polarized laser nor polarized X-ray.
Generation of coherent X-ray by using optical resonators has been reported, for example, in the patent literatures (Patent Literatures 5-8, Non-Patent Literature 4).
The Patent Literature 5 has disclosed the method and apparatus to generate coherent X-ray through the laser inverse Compton scattering using the optical resonator. However, the Patent Literature 5 nowhere describes or suggests methods and apparatuses as intend to generate coherent X-ray through irradiation of interference fringes being formed by interference of polarized laser beams with electron beams.
The Patent Literature 6 has disclosed the method and apparatus to generate coherent X-ray through the laser inverse Compton scattering using the optical resonator. However, the Patent Literature 6 nowhere describes or suggests methods and apparatuses as intend to generate coherent X-ray through irradiation of interference fringes being formed by interference of polarized laser with electron beam.
The Patent Literature 7 and Non-Patent Literature 4 describe the method and apparatus which conduct coherent addition of laser light through laser interference in the focal position of laser paths in the four-mirror optical resonator, thereby generation of strong and coherent laser and generation of coherent X-ray by irradiation of the generated strong and coherent laser with electron beam. However, the Patent Literature 7 nowhere describes or suggests methods and apparatuses as intend to generate coherent X-ray through irradiation of interference fringes being formed by interference of polarized laser with electron beam.
The Patent Literature 7 is same as the Patent Literature 1, but the referred sections are different.
The Patent literature 8 has disclosed the X-ray generator embedded in a vacuum chamber, comprising: a pulse compressor to compress laser into femtosecond laser; a collection mirror to collect femtosecond laser; a gas supply unit to supply Ar-gas plasma jet; wherein, Ar-gas plasma jet supplied by the gas supply unit is irradiated with the femtosecond laser generated by the pulse compressor through the collection mirror, coherent characteristic X-ray is generated thereby. The X-ray generated by this method may be coherent characteristic X-ray. However, the Patent Literature 8 is not an invention in regard to the method and apparatus to generate coherent X-ray through the laser inverse Compton scattering using an optical resonator.
In addition to the above Patent Literatures, enormously large numbers of patents and non-patent literatures relating to coherent laser and laser interference fringes have been known. On the other hand, it has been known from the above Patent Literatures 5-7 that coherent X-ray is generated by irradiation of laser inside the optical resonator with electron beam. Therefore, it may be easily conceivable to generate coherent X-ray by irradiation of laser interference fringes or coherent laser with electron beam. However, the optical resonator as intends to generate coherent X-ray by irradiation of polarized laser interference fringes with electron beam has been unknown to the best of the present inventor knowledge. This is due to that the present inventor has found the principle to generate coherent X-ray by irradiation of laser interference fringes being formed with polarized laser interference insides an optical resonator with electron beam, which has ever been unknown, as explained later.
The Patent Literatures 5-7 describe generation of coherent X-ray by irradiation of coherent laser in the optical resonator, but coherence property of the generated X-ray may be incorrect. Because, X-ray being generated by collision of conventional laser beam of several tens microns in size and conventional electron beam of several tens microns in size may be coherent in an extremely short range of initial time and space, however, phases and amplitudes of generated X-ray instantaneously become random in the spatial divergence processes.
In view of the above described circumstances, the present inventors have presented an outstanding three-dimensional-four-mirror (3D-4-mirror) optical resonator, in which a pair of flat mirrors and a pair of concave mirrors are three-dimensionally arranged, that produces high strength of polarized laser to induce laser inverse Compton scattering (Patent Literature 9). The 3D-4-mirror optical resonator equipping a polarization control system is able to prepare selectively a polarization component of polarized laser, either right-circularly polarized laser or left-circularly polarized laser, through the electrically alternate switching of polarization. Therefore, the above 3D-4-mirror optical resonator further equipping an electron beam radiation device is capable of preparing right-circularly polarized X-ray or left circularly polarized X-ray through irradiating circularly polarized laser of different parity with electron beam (Non-Patent Literature 1, Non-Patent Literature 2). Also, the present inventors have presented the two-dimensional four-mirror (2D-4-mirror) optical resonator in which a pair of flat mirrors and a pair of concave mirrors are arranged in the two-dimensional plane (Non-Patent Literature 3). The 2D-4-mirror optical resonator equipping a polarization control system may be able to prepare alternately a polarization component of polarized laser, right-circularly polarized laser or left-circularly polarized laser for circularly polarized laser and horizontal-linearly polarized laser or vertical-linearly polarized laser. Therefore, the above 2D-4-mirror optical resonator further equipping an electron radiation device may be capable of preparing right-circularly polarized X-ray or left-circularly polarized X-ray corresponding to circularly polarized laser and horizontal-linearly polarized X-ray or vertical-linearly polarized X-ray corresponding to linearly polarized laser through irradiating polarized laser of different parity with electron beam. In the present invention, the above parity means right-circular polarization or left-circular polarization for circular polarization and horizontal polarization or vertical polarization for linear polarization.